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Biomedical subjects

K B Sahay

Publications and source records attributed to K B Sahay.

13 recordsLinked to original sources
PubMed1998

Interplay of matrices in cartilage synovial fluid combine under moderate & high loadings.

Interplay of the constituents of the articular cartilage synovial fluid combine and its role was examined through the biochemical and rheological studies on bovine joints. The results showed an inverse relationship between the changes in the hyaluronic acid of synovial fluid and the proteoglycans content in articular cartilage together with alterations in the rheological properties of synovial fluid. The study indicated that the inter-movement of fluid solutes across the cartilage and synovial fluid may have an important role in the pathophysiology of osteoarthritis.

Animals↗
PubMed1994

Effect of moderate & high loadings on the proteoglycans & water content of bovine knee joint articular cartilage.

Variations in proteoglycans and water content of the knee joint cartilage were found to occur when the joint was subjected to articulating motion under moderate and high loadings. It was found that at a moderate load of 150 kg there were an increase in the percentage of proteoglycans but the percentage decreased when the joint was articulated at a high loading of 300 kg. It has also been observed that the ratio of water content and the proteoglycans decreased at moderate load, whereas the ratio increased at high load. The observed changes in proteoglycans and water content in extracellular matrix with moderate and high loadings suggested that articular cartilage properties respond to mechanical stresses.

Animals↗
PubMed1992

Elastomechanical characterization of brain tissues.

The fluid-induced changes in the intracranial pressure which have important clinical implications are believed to be largely determined by the elastomechanical properties of the brain tissues. To define and evaluate the elastomechanical characteristics of the brain tissues a nonlinear hyperelastic hollow spherical shell has been employed to model the craniospinal complex for its fluid-induced intracranial pressure volume changes. The strain energy function proposed by Hart-Smith has been used to derive the constitutive equations. In 10 dogs, fluid has been infused in the lateral ventricle of the brain. The resulting changes in the ventricular fluid pressure (VFP) and the epidural pressure (EDP) have been recorded. The plot of pressure as a function of volume increases first, reaches a maximum, decreases, reaches a minimum and increases monotonously. The values of maximum and minimum pressures (pv max and pv min) due to fluid infusion are found to be, respectively, 42.4 +/- 15.4 mmHg and 33.1 +/- 12.2 mmHg. The pressure achieved the maximum and minimum values with infusion of 0.19 +/- 0.09 ml and 0.51 +/- 0.15 ml of fluid, respectively. The elastomechanical parameters of the Hart-Smith function that characterize the brain tissues have been evaluated by matching the experimentally obtained pressure-volume curves with the corresponding model generated curves. It is found that the agreement between the experimentally obtained pressure-volume curves and the corresponding Hart-Smith profile is satisfactory at a high inflation level but less so at the lower inflation level.

Animals↗
PubMed1991

Morphological changes in the bovine articular cartilage subjected to moderate and high loadings.

This study aims at examining the morphological changes in the cartilage structure of the bovine knee joint when the amputated joints are subjected to (a) a moderate load of 150 kg and (b) a high load of 300 kg and fitted on a knee joint articulating machine at 45 cycles/min for 2 h. The scanning-microscopic study of the surface structure of the experimental and control cartilage shows no appreciable change in the surface morphology of the cartilage when subjected to the moderate load of 150 kg. However, in the case of the high load (300 kg) there is appreciable change in the fibrillary structural pattern of the surface morphology. Histologically too, no appreciable change was noticed when subjected to moderate loadings, but in the case of high loading the cartilage develops roughness of the surface with occasional small clefts.

Animals↗
PubMed1991

Shear properties of articular cartilage of a bovine knee joint subjected to moderate and high loads: an experimental study.

Freshly excised bovine knee joints were subjected to oscillation under constant load on a specially designed knee joint articulating machine with the joints subjected to moderate and high loadings of 1471.5 and 2943 N respectively. Instantaneous and equilibrium shear moduli of the articular cartilage obtained from the experimental knee joints were measured on a mechanical indentor (DuPont 943 TMA) and compared with the corresponding values of the shear moduli of the cartilage obtained from the control knee joints. At moderate load, both the instantaneous and the equilibrium shear moduli exhibit significant increase in their values. However, at high load the constant shear moduli showed a decrease in its value whereas the value of the equilibrium shear modulus was observed to increase slightly.

Animals↗
PubMed1991

Relation between epidural and ventricular pressures in canine brain: an experimental study.

Complications of epidural pressure (EDP) monitoring are much less severe than those of ventricular fluid pressure (VFP) monitoring. Hence, an insight into the relationship between the epidural and the ventricular pressures is of clinical importance. The pressure volume response as obtained during infusion tests performed on dogs can be categorized into two phases: (i) the latent phase and (ii) the monotonic rise phase. During the latent phase the VFP first rises to a maximum and then falls to a minimum, but these changes in VFP are not reflected in EDP. The latent phase is followed by the monotonic rise phase during which both VFP and EDP rise simultaneously and monotonically. Although the changes in VFP and EDP are similar the epidural pressure remains consistently less than the ventricular fluid pressure. Hence, changes in VFP can be estimated by monitoring EDP during the monotonic rise phase but not during the latent phase.

Animals↗
PubMed1990

Intracranial pressure-volume response in dog subjected to repeated infusion tests: an experimental study.

Several experimental studies have been made in the past to try to understand the nature of the fluid-induced changes in the intracranial pressures of the animals by infusing fluid into their craniospinal complex. The objective of the present investigation was to study the changes in the characteristics of the ventricular and epidural pressure-volume curves when a dog was subjected to repeated fluid infusion tests. The animals were subjected to three cycles of infusion tests with a time interval of either 10 min or 2 h between any two successive tests. An infusion test repeated 10 min after the preceding test exhibited a significant change in the characteristics of the ventricular fluid pressure (VFP) response but not in the epidural pressure (EDP) response. However, in the case of an infusion test which was repeated 2 h after the preceding test, it was observed that both the VFP and EDP responses remained the same as those found in the first infusion test.

Animals↗
PubMed1988

A finite deformation model of infantile hydrocephalus.

Clinical data obtained about intracranial pressure volume experiments abound in the literature. However, what is lacking is a proper interpretation of the data. A nonlinear hyperelastic model is proposed in this paper which is more realistic and simulates successfully the various states and stages of infantile hydrocephalus which have hitherto been considered puzzling. Strain energy function incorporating two and three constants have been employed to develop the constitutive equations and pressure-volume curves have been plotted for arbitrary values of the constants. The available clinical data can be employed through the proposed model to evaluate the status of hydrocephalus and also to arrive at suitable measures to relieve the intracranial pressure and ventricular dilatation.

Algorithms↗
PubMed1984

A nonlinear hyperelastic model of pressure volume function of cranial components.

The pressure-volume relationship (PVR) in the intracranial cerebrospinal fluid space has been a matter of investigation for quite sometime. The quantitative considerations of the PVR are believed to have important clinical implications, and attempts have been made to study the pressure-volume characteristics associated with a variety of disease states. Efforts have been made by researchers to understand the phenomenon in terms of mechanics. The major drawback has been that almost all researchers have invoked in their analyses, concepts from linear infinitesimal elasticity to explain the intracranial PVR. In this paper we have proposed a more realistic hyperelastic model to explain the observed PVR of the intracranial complex. The proposed model provides a better approximation to the intracranial P-V response than those proposed by previous investigators. The model highlights also the parameters that are relevant to characterise the intracranial tissues.

Animals↗
PubMedDate not supplied

Biomedical equipment and medical services in India.

Varieties of Biomedical Equipment (BME) are now used for quick diagnosis, flawless surgery and therapeutics etc. Use of a malfunctioning BME could result in faulty diagnosis and wrong treatment and can lead to damaging or even devastating aftermath. Modern Biomedical Equipments inevitably employ highly sophisticated technology and use complex systems and instrumentation for best results. To the best of our knowledge the medical education in India does not impart any knowledge on the theory and design of BME and it is perhaps not possible also. Hence there is need for a permanent mechanism which can maintain and repair the biomedical equipments routinely before use and this can be done only with the help of qualified Clinical Engineers. Thus there is a genuine need for well organized cadre of Clinical Engineers who would be persons with engineering background with specialization in medical instrumentation. These Clinical engineers should be made responsible for the maintenance and proper functioning of BME. Every hospital or group of hospitals in the advanced countries has a clinical engineering unit that takes care of the biomedical equipments and systems in the hospital by undertaking routine and preventive maintenance, regular calibration of equipments and their timely repairs. Clinical engineers should be thus made an essential part of modern health care system and services. Unfortunately such facilities and mechanism do not exist in India. To make BME maintenance efficient and flawless in India, study suggests following measures and remedies: (i) design and development of comprehensive computerized database for BME (ii) cadre of Clinical engineers (iii) online maintenance facility and (iv) farsighted managerial skill to maximize accuracy, functioning and cost effectiveness.

Biomedical Engineering↗
PubMedDate not supplied

A power spectral study of surface EMG of muscles subjected to non-repetitive task.

For a proper understanding and interpretation of the changes in the power spectral characteristics of surface EMG from any fatigued muscle of a worker employed on repetitive assembly line tasks, it is important to study first the changes in the spectral characteristic of the surface EMG of the same muscle of the worker assigned with non-repetitive tasks. The information obtained from the EMG study with non-repetitive tasks would serve as a control to identify and evaluate the changes in the power spectral features of the surface EMG of the muscle due to, in particular, the repetitive nature of the task under similar work environment. In this study the EMG signals from thenar fascia and biceps of two healthy workers engaged in non-repetitive tasks in an electronic industry have been recorded in the morning (before the start of the work) and again the evening (after the completion of day's work). The frequency wise distribution of the number of peaks (NP) and the power content (PC) of the signal have been evaluated within the range of 60-200 Hz. It is found that there is no significant difference in the frequency wise distribution of NP and PC in the power spectrum of the EMG signals recorded in the morning and evening.

Adult↗